Electrode assembly for discharge tubes



Aug- 8, 1944 N. B. Kmm 2,355,083

ELECTRODE ASSEMBLY FOR DISCHARGE TUBE Filed Jan. 3,. 1941 2 Sheets-Sheet1 ls- Imi m Iulmm |9 S: I i

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No RMAN B. KRIM,

ATTY.

Aug. 8, 1944.

vN. B. KRIM ELCTRODE ASSEMBLY FOR DISCHARGE TUBE Filed Jan. 5, 1941 2Sheets-Sheet 2 Y: m. w m NRWA F, 0K EB AV .WN A M n Y., NB Z. Gt. F

Patented ug. 8, 1944 2,355,083 o Emoment: ASSEMBLYr Foa DISCHARGE 'massNuman B. Krim, Cambridge, Mass., assis-nor, by

mesne assignments, to Raytheon Manufacturing Company, Newton, Mass., acorporation of Delaware Application January 3, 1941, Serial No. 373,006

f 9 Claims. (Cl. Z50-27.5)

This invention relates to an electrical space discharge tube of thevacuum type in .which the dimensions of the tube are reduced torelatively small value s. Such tubesare particularly useful` in smallportable devices, such as hearing aids and pocket radios. Devices ofthis kind are so small in size that they may be carried by the userconcealed in the clothing. Therefore, it is important that the tubes bemade extremely small in order that they may be utilized in such 'I'heforegoing and other objects of this inven-V tion will -be bestunderstood from the following description of an exempliiication thereof,reference being had to the accompanying driwings wherein:

Fig. 1 is a cross section of my novel tube taken along line I I of Fig.2;

Fig. 2 is a cross section taken along line 2 2 of Fig. l;

Fig. 3 is a longitudinal cross section of the tube shown in Fig. 1,taken along line 3 3 of Fig. 2;

Fig. 4 is a cross section of the lower portion of the tube taken alongline 4 5 of Fig. 2; and

Fig. 5 is a fragmentary cross section of a. detail of the tube vtakenalong line 5 5 of Fig. 2.

The tube assembly illustrated is contained Within a sealed envelope I ofsome suitable material such as glass. 'llhe electrodes consist of a pairof anode plates 2 2, a iilamentary cathode 3, and a plurality of grids5, and 6 interposed between the' cathode and the anode plates. Properspacing and support of the electrodes is provided by upper and lowerinsulating spacers 1l and 8, preferably of mica. 'I'he edge of thesespacers is provided with a plurality of resilient projections 9 whichare adapted to resiliently engage the inner walls of the envelope I.

The anode plates 2 2 are each mounted upon and I2 are inserted 4throughholes in the upper spacer 1 and the frame I0 is pushed down until itsstraight top portion engages the top of said insulating spacer 1.Thereupon the associated anode plate 2 is welded to the side arms II andI2 with the upper edge of said anode plate engaging the lower side ofthe upper insulating spacer As indicated in Fig. 2, the anode plates 2may each be formed with grooved side edges to more readily receive theside arms II and I2 to be welded thereto. Thereupon the side arms II andI2 of each of the frames I0 are inserted through openings in the lowerinsulating spacer 8 which in this way is assembled in place on the anodestructure. A double-armed anode bracket I3 is then welded to the lowerends of each of the side arms I2. Each arm of the anode bracket I3 isprovided with a pair of ears I4 whichengage the lower side of theinsulating spacer 8. In this hway, the anode assembly is completed withthe two anode plates 2 electrically connected and securely fastened inplace on the insulating spacers i and 8.

'Ihe grids 4, 5 and 6 are wound upon and supported by grid side rods I5I5, I 6 I6, and Il I'l respectively. These side rods likewise projectthrough openings in the upper and lower insulating spacers l and 8. Theassembly of these grids on the insulating spacers may take place at anyconvenient time during the assembly of the electrode structure. One ofthe side rods I'I of the grid Ii is adapted to support the lament 3 aswill be described below. In' order to prevent motion of the grid E andits associated side rod II relative to the spacers 'l vand S, a pair oftabs I8 and I9 are welded on to one of the side rods Il, engaging thelower side of the insulating spacer d and the upper side oi theinsulating spacer Il respectively. A. ring 2U of getter material may beconveniently supported on the electrode assembly by being welded to theupper end of one of the side rods Il.

`The lament 3 is supported between a conducting spring member 2i at itsupper end' and a lament clip 22 at its lower end.A The spring member 2iis welded at one end to the upper end of the iilamentary cathode 3 andat its other end to one of the side rods Il. The lower end of thefilament ii is Welded to the filament clip 22 by means of a connectortab 25. The lamentary cathode 3 is retained in the apexes of a pair oftriangular slots 23 formed in the upper and lower insulating spacers 'Iand 8, through the tension exerted on said filament by the spring 2l.

The form of these triangular slots and their relationship to the cathodesupporting arrangement is more fully described and claimed in thecopending applicatio of Alan C. Rockwood for "Discharge tube s ers,Serial No. 353,108, nled August 1'7, 1940, now Patent No.' 2,266,080,dated December 16, 1941. l'Ihe filament clip 22 is made in a V-shapewith two end portions 24-24. These end portions are firmly secured tothe insulating spacer 2 by being inserted through holes in said lowerinsulating spacer and by being bent over so as to engage both the topand the bottom of said insulating spacer 2. In the small spaceavailable, the points at which the ends 24 of the filament clip' 22are'secured to the insulating spacer 8, are substantially in line withthe anode plates 2-2. In order to provide space for the ends 2l, and toavoid electrical contact there- `with, the anode plates 2--2 areeach cutaway to provide an opening- 26 adjacent the respective ends 2| of theclip'22.

A plurality of lead-in conductors 21, 22, 28, 20 and 2l, are providedfor the electrodes 2, 5, 2, l,

assaoss and 2 respectively. For this purpose, the lead-in 21 is weldedto the anode bracket I2, ltheklead-in 22 is welded to one of the siderods I8 of the grid 5, the lead-in 29 is welded to the iilament clip 22,the lead-in 20 is welded to one oi.' the side rods I5 of the grid l, andthe lead-in 2i is welded to one of the side rods I1 of the grid 6. Allof the lead-.ins are sealed through la lower press 22 formed externallyon the envelope I. In this way the electrode assemblyis retained inplace within said envelope and external electrical -connections areprovided to the respective electrodes.

One of the main factors determining the maximum width of the electrodeassembly is the space necessary for the i'll'ament 2, the side rods II,II and I1, and the associated grid windings. -A certain minimum amountof space is necessary to be left between .these various elements. Itwill be noted that the filament 2 occupies a minimum amount of space bybeing made as a straight nlament, the return connection for said lamentbeing made through one of the side rods I1. In

the present structure, I have also decreased the,

overallfdimensions by making the width of each of the plate elements 2narrower than the maximum width of the'grid 2. This is possible becausethe electron stream which passes from the lament 2 to the `plates 2 issubstantially nonexistent or non-eiective upon the dimensionsv of theplate as described above. By narrowing the plate in this way, the sidesof the glass envelope I in the cross section as illustrated in Fig. 2can be curved inward soonerv'thus decreasing sub'- stantially the minorwidth of the tube, permitting the use of the comparatively iiat tubecross section illustrated.

. From Figs. 3 and 4 it will be seen that the sides of the anode bracketl2 and the lament clip 22V are tapered toward the bottom portionsthereof.

'This is done so that these members do not come lof the lament clip 22,a considerable amount of space is saved and the spondingly reduced.

' By the above arrangement, I have,l been able size of the tube corretoproduce tubes as illustrated herein of very small size on a masslproduction basis. For example,

a tube exactly as described above has been constructed withthe outsideoverall dimensions ol spaced from the tube being .285 man thick. .sesinch wide.- ,and 1 V, inches long.

Of course it io be understood that this invention is not 'limited to theparticular details as described above as many equivalents will suggestthemselves to those skilled in the art. For example, the invention canbe applied to tubes ofother types in which otherlnumbers oi' grids mightbe used. Various other changes embodying the teachings of this inventionwill suggest themselves to those skilled in the art.

What is claimed is:

1. An electrical spacedischarge tube comprising an insulating spacer, ametal frame member having a portion engaging one side of said spacer anda portion projecting through said spacer, an electrode secured to saidlatter portion and engaging theother side of said spacer 'and at leastone additional electrode spaced from said rst named electrode by saidspacer. A,

2. An electrical space discharge tube comprising an insulating spacer, ametal frame member having a portion engaging one side of said spacerelectrode spaced from said ilrst named electrode by said spacers.

3. An electrical space discharge tube comprls" ing an insulating spacer,a U-shaped metal frame member having its end portion engaging one sideof said spacer and its` leg portions projecting through said spacer, anelectrode secured to said leg portions and engaging the other side ofsaid spacer and at least one additional electrode said iirst namedelectrode by' said spacer. f

4. An electrical space' discharge'tube compris- I ing an insulatingspacer, a U-shaped metal frame member having its end portion engagingone side of said spacer and its leg portions projecting through saidspacer, an electrode secured to said leg portions and engaging the otherside of said spacer, a second insulating spacer, said electrode engagingone side of said second spacer, said leg portions of said frame memberalso projecting through said second insulating spacer, a stop membersecured to one of said leg portions and 'rst named electrode by saidspacers.

5. An electrical space discharge tube comprising an insulating spacer, apair of metal frame 60 members eachhaving a portion engaging one side ofsaid spacer and a portion projecting through said spacer, an electrodeelement secured to said latter. portion and engaging the other side ofsaid spacer, a secondinsulating spacer, said electrode element engagingone side of said second spacer, said latter portion of said framelmember also projecting through said second insulating spacer, anelectrically conducting yoke member secured to and electricallyinterconnecting the latter portions of both of said frame members andengaging the other side of said second spacer and at least oneadditional electrode spaced from said nrst named electrode by saidspacers.

' 6. An electrical space discharge tube comprising am insulating spacer,a pair -of U-shaped metal frame members each having its end portionengaging one side of said spacer and its leg portions projecting throughsaid spacer, an electrode element secured to said leg portions andengaging the other side of said spacer, a second `insulating spacer,said electrode element engaging one side of said second spacer, said legportions of said frame` member also projecting through said secondinsulating spacer, an electrically conducting yoke member secured to andelectrically interconnecting both of said frame members and engaging theother side cf said second spacer and at least one additional electrodespaced from said iirst named electrode by said spacers. Y, l

'7. An electrical space discharge tube comprising an insulating spacer,a relatively extended electrode closely adjacent said spacer, aconducting fastening member secured to said insulating spacer and lyingsubstantially in the plane of said electrode, said electrode beingprovided with an opening adjacent said fastening member whereby saidfastening member projects into said opening and is insulated from saidelectrode.

8. An electrical space discharge tube comprising an electrode assemblyhaving a planer spacer at one end thereof, an envelope enclosing saidelectrode assembly and having a non-circular cross-sectional areaproviding a plurality of cor- 'ner regions of substantially increasedcurvature, the distances between diagonally opposite corner regionsconstituting the maximum straight line distances within saidcross-sectional area, said spacer likewise having a. plurality ofcorners prol jecting into and intimately contacting the inner wall ofsaid envelope at said corner regions. whereby said spacer can beinserted into said envelope only in a predetermined orientation.

9. An electrical space discharge tube comprising an electrode assemblyhaving a. planer spacer at one end thereof, an envelope enclosing saidelectrode assembly and having a cross-sectional area with onecross-sectional dimension substantially shorter than another,v producingfour corner regions of substantially increased curvature, the distancesbetween diagonally opposite corner regions constituting the maximumstraight line distances within said crossfsectional area, said spacerhaving likewise four corners projecting into and intimately contactingthe inner wall of said envelope at said corner regions, whereby saidspacer can be inserted into said envelope only in a predeterminedorientation.

NORMAN B. KRIM.

